This invention relates to saw apparatus, and more particularly to such apparatus which includes multiple saws mounted on a saw arbor with such saws being laterally adjustable on the arbor. Saw apparatus of this description is exemplified by a so-called gang rip saw, which includes multiple circular saws which are adjusted along the arbor and laterally of each other to change the width of the boards cut by the machine.
More specifically, this invention concerns an improvement in saw apparatus of the type illustrated in my earlier U.S. Pat. No. 3,202,189. The rip saw disclosed in this patent includes an elongate power-driven saw arbor which is splined, i.e. provided with elongate keyways or channels extending axially therealong. Saw collars which encircle the arbor and which are used in the mounting of circular saws are movable axially to and fro on the arbor. A pair of rigid keys or shifter bars seated within channels provided on diametrically opposite sides of the arbor are joined at one set of ends to each saw collar. These keys or bars have opposite ends secured to what is referred to in the patent as a shifter mechanism. Movement of the collar along the arbor is produced through movement of the shifter mechanism in a direction extending axially of the arbor, which movement through the pair of bars is transmitted to the collar secured to the opposite ends of these bars.
The apparatus just briefly described and disclosed in my earlier patent has proven to be a very satisfactory machine in affording, as it does, the capability of shifting multiple circular saws along an arbor with such saws being positionable relatively close together on the arbor, enabling the production of narrowly cut boards in a single pass through the machine. While the saw apparatus has proven to be highly successful, it has been subject to certain deficiencies which have proved troublesome in manufacturing the machine, even when the most careful manufacturing procedures are followed.
Further explaining, as earlier conceived by me, two shifter bars or keys were joined to opposite sides of a saw collar. This was to insure that the collar when moved would have a force applied to regions disposed on diametrically opposite sides of the arbor whereby the collar would be shifted without skewing. With the arbor stationary, a collar is best shifted along the length of the arbor using a pair of such diametrically opposed shifter bars or keys. However, with the provision of two keys, in assembling the keys, the collar and the shifter mechanism, extremely close manufacturing tolerances must be followed if the collar in the final assembly is to have a position where the plane thereof is exactly normal to the arbor axis. Any slight canting or skewing of the collar in its final assembled condition, even to the extent that one side is displaced axially from the other a few thousandths of an inch, results in vibration, burned saws, and saw cuts of greater than desired width. Furthermore, and in this connection it should be remembered that a saw arbor may be rotated in speeds in excess of 3000 rpm, in some instances it has been noted that while the saw collar is shifted easily with the arbor stationary, with the arbor rotating at cutting speed, the saw collar becomes essentially locked to the arbor and unshiftable.
This invention is based on the discovery that a body such as a collar encircling a shaft and rotating with the shaft tends, under the action of centrifugal force, to assume a position wherein the plane of such body is normal to the shaft axis. Further, if a means is provided for shifting this body which is anchored to this body at a single point, which anchoring point further rotates with the shaft and body, when an axial thrust is imparted to the body through this single anchored connection, binding does not occur. Apparently what happens is that the body initially tends to be skewed slightly, with the body rapidly returning to a plane normal to the axis of the shaft, but displaced along the length of the shaft to the extent of the original slight skewing.
Following the invention, binding of a saw collar on the arbor, as the result of rotation of the arbor at high speeds, does not occur. The need for connecting within close tolerances two shifter bars between a saw collar and an associated shifter mechanism, is eliminated. Also eliminated are other problems associated with a slightly mis-mounted saw collar, such as vibration, noise, burned out saws, etc. Other advantages realized comprise a savings in manufacturing time, a savings in the number of shifter bars needed for a given machine, a reduction in the friction caused by the shifter bars, increased arbor strength and reduction in the time required to manufacture an arbor, and increased stability in a collar and in the manner in which the collar is mounted on an arbor.
These and other objects and advantages are attained by the invention, which will become more fully apparent on reading the following description, which is to be taken in conjunction with the accompanying drawings, wherein;